A known farm implement employs a drive axle and wheel supporting hub connected by a mechanism which allows the axle to be engaged with or disengaged from the hub. This permits one to engage the hub while the implement is being used and to disengage it when the implement is being towed between fields. This substantially reduces the wear on the axle and increases its useful life. The disengagement is effected by depression of the axle shaft. Known mechanisms for selectively changing the position of the shaft to either a depressed position for disengaging the drive hub or an outward position for engaging the drive hub are cumbersome to use.
One conventional construction is a reversible disengaging plate having a projection. The plate is bolted to the hub assembly such that the projection pushes the shaft inward in one position, and allows the shaft to move outward when the plate is bolted to the hub in the reversed position. The plate must be removed, reversed and reinstalled each time the drive hub is engaged or disengaged.
The general operation of another such hub system is described in Gilcrest, U.S. Pat. No. 4,453,852, the disclosure of which is incorporated herein by reference. Gilcrest describes a hub engaging and disengaging device in which a plunger is held in the inward position by two balls. The plunger is moved from the inward, disengaged drive position to the outward, engaged drive position, by pushing the balls into radially located grooves by depressing a pair of shiftable control members having these grooves located in a lower portion thereof. To disengage the drive, the plunger is depressed, allowing the balls to locate against a shoulder of the plunger and allowing the control members to move axially outward.
Other patents showing different arrangements for engaging and disengaging a hub include Hegar, U.S. Pat. Nos. 3,442,361; Kapusta, 184,258; Erickson, 4,555,197; Kleespies, 4,089,610, and Williams, 3,753,479.